A High Contrast Hybrid Electrochromic Device Containing PEDOT, Heptyl Viologen, and Radical Provider TEMPO

An anodic radical provider, 2,2,6,6-tetramethyl-1-piperidinyloxy (TEMPO), and two electrochromic (EC) materials, poly(3,4-ethylenedioxythiophene) (PEDOT) and heptyl viologen , were utilized to fabricate a hybrid electrochromic device (ECD). PEDOT and were used as film and solution-type cathodic EC materials, respectively. The ECD exhibited two-stage redox reactions with high absorbance attenuation in the visible region. With the variation in the operating voltage, a maximum transmittance change of 20% at 610 nm was observed in the first stage (−0.5 to 0.8 V), whereas a maximum of 68% was observed in the second stage (0.8–1.5 V). Furthermore, fast switching times of 6.9 and 2.1 s were estimated for bleaching and darkening, respectively. The coloration efficiencies at 610 nm were 171.9 and for the first and second stages, respectively.